Gaea

From MTG Salvation Wiki

Gaea is a goddess of Dominaria. She is believed to be the plane's protector and possibly its creator. Her role in this regard could be compared to O-Kagachi of Kamigawa, who was the embodiment of all mana and/or magic of the plane.

Very little is known about her, which makes classifying her very difficult. Many elves worship her as a goddess, and Multani prayed to her, and though she never answered directly, he always sensed the answer. It could be that she is just a metaphor and does not exist at all, but many characters, like Urza or Freyalise seem to confirm her existance in what they say.

Yawgmoth believed she is in fact Rebbec and has gone through a similar transformation as he himself experienced. Not many storyline fans believe Yawgmoth's claims, but it has muddled up the debate about Gaea quite a bit.

In pre-revisionist continuity Gaea was just a green based planeswalker.